In recent years, in order to cope with crashes/rear-end collisions occurring due to driver distraction, a vehicle control system, such as a vehicle's automatic brake or an auto cruise control, which utilizes a variety of sensors has been put into production for the purpose of reducing vehicle crashes. In the same system, it is common that ahead of a vehicle on the front side, a pedestrian, or the like, is recognized by sensing, and that a warning is given using a warning sound, or the like, when there is a danger of collision by still keeping on driving, and the brake is automatically applied when there is no remediation even after the warning.
However, in the heretofore mentioned vehicle control system, it may happen that a collision is avoided by the brake operating automatically, but as the same system just assists in making up for the driving deficiency of the driver, there is no guarantee that the system operates under any circumstances, and the driver him/herself eventually has to be certain to drive safely on the driver's own responsibility. Because of this, the system has not reached a fundamental solution to the problem of encouraging the driver to drive safely so as to prevent the driver him/herself from performing a dangerous action while driving. As the same system is such that a warning sound is emitted although the driver is aware of danger, the system may become annoying to the driver.
Also, the citation list shows a technology of reducing the driver's discomfort in the situation of lane departure, illustrating that the discomfort is reduced by turning down the warning sound when the driver starts a lane keeping operation. However, as the warning sound is emitted invariably when there is a lane departure, the warning sound is also emitted, for example, when the driver consciously departs intentionally from a lane within the range of safe driving (for example refer to PTL 1).